#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pii = pair<int, int>;
#define rep(i, a, b) for (int i = (a); i <= (b); i++)
#define per(i, a, b) for (int i = (a); i >= (b); i--)
#define endl '\n'
const int N = 2e5 + 5;
const int M = 1e6 + 5;

int n, m;
int a[N];
int b[M];
int main() {
  ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  cin >> n;
  rep(i, 1, n) cin >> a[i];
  int ans = n + 1;
  rep(i, 1, n) {
    if (b[a[i]]) ans = min(ans, i - b[a[i]] + 1);
    b[a[i]] = i;
  }
  if (ans > n)
    cout << -1;
  else
    cout << ans;
  return 0;
}